Composition of glass.



E. WEINTRAUB.

COMPOSITION 0F GLASS.

APPLICATION FILED IIIAY 8. 1912.

1,191,630. Patented July 18, 1916.

Jfs TUR NEY UNITED s'rATEs PATENT oEErcE.

EZECHIEL WEINTRAUB, 0F LYNN, MASSACHUSETTS, ASSIGNOR T0 GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

COMPOSITION OF GLASS.

To all whom t may concern Be it known that I, EzEoHrEL WEINTRAUB, a citizen of the United States, residing at Lynn, county of Essex, State of Massachu- A setts, have invented certain new and useful Improvements in Compositions of Glass, of

which the following is a specification.

The present invention relates to envelops of quartz and in particular to an improved seal between quartzand a metallic conductor.

Patent 910,969 describes a seal for quartz containers in which a metallic conductor is sealed into a glass, the composition of which merges gradually into quartz with a progressively decreasing constituents of the glass. I have found -when experimenting with a large number of glasses that a `sodium-l magnesium boro-silicate which can 'be obtained in the market as low expansion glass, has the property of forming fusions with silica in any proportion with the formation of Aexceptionally strong tough glass for all proportions. The glasses thus produced are amorphous masses devoid of crystallization and have all the desirable propertiesl whichfare characteristic of what is termed a glass.

My invention, comprises new glasses of high melting point and low coeicient of lexpansion and richer in silica than any glasses produced so far, that is, in excess of about 73% silica. In view ofthe fact that these glasses are tough, and free from crystallization they could be used for any purposes where the above enumerated properties are desirable.4 l

In the accompanying drawings, Figure 1 illustrates a seal` in a silica envelop in which a tungsten or molybdenum wire is sealed directly into low expansion glass and Fig. 2 indicates a modification Ain which a platinum conductor is employed. l

According to one method of carrying'out my invention, low expansion glass is intimately mixed with progressively larger quantities of silica to make a series'of melts. A boro-silicate suitable for this purpose has the following composition: silica, Si02, 72 to 73 per cent.; magnesium oxid, MgO, 3 to 4. per cent.; boric anhydrd, B203, 11 to Specification of Letters Patent.

vthat this composition is illustrative.

proportion of basicv Patented July 18, 1916. Application led May 8, 1912. Serial No. 695,936.

'12 per cent.; sodiumvoxid, NazO, 12 to'13 per cent. It will be understood,lof course,

Potassium might be substituted for sodium.

A glass of the above composition. or itsv equivalent, is veryfinely powdered and to separate portions ground quartz is added to the extent of about 15, 30, 50, 70 and 85% of quartz to 85, 70, 50, 30 and 15% respectively of glass. The proportions4 need notbe strictly adhered to' but are given for the purpose of illustration.- These mixtures are fused to form glasses having an excess of 73% silica, as progressively larger portions of quartz are incorporated in the several portions of low expansion glass. These glassy mixtures have a coeiiicient of expansion intermediate between 3.5x10-6, which corresponds to low expansion glass, and about .6x10'6, which correspond-s toquartz.` Said glasses are built up at the end of the quartz tube by means of the oxygen blowpipe or arc so as to secure a progressive change of composition from silica to low expanslon glass. For example, to the end of a quartz tube 1 'a ring or a layer of the vitreous mixture comprising 85% of quartz and 15% of Iglass is applied and heated so as to unite land intermingle it with the quartz tube. Thisheating causes a further blending ofthe two materials so that the composition changes` by almost imperceptible stages from pure quartz to the material containing an appreciable amount of admixture. This process is then relower amount of admixed silica'. By working in this way the basic constituents of the boro-silicate are progressively increased when receding from the region of pure silica 2 of lowexpansion glass having the above indicated composition into which a tungsten or molybdenum wire '3 is sealed in the usual manner. 'A low expansion, boro-silicate glassgof the above composition has 'a coeiicien-t of expansion of about 3.5x10-8. I have vfound that tungsten, W, or molybdenum, Mo, which has about the samel coeiicient of expansion is readily wet by this glass and may be used to make a perfectly gas-tight seal as described by me in my copeated with a vitreous material containinga y until finally the tube is closed with a portion pending application Serial No. 697,192, filed May 14, 1912, patented September 21, 1915, Patent No. 1,154,081.

ln case it is desired to `use a leadingl in Wire consisting of platinum, Fig. l2, it is necessary to join by fusion to the boro-silicate other glasses having a progressively vhigher coeiicient of expansion until the co-` What li claim as new and desire to secure -by Letters Patent of the United States, is

1. A tough, strong, glassy material consisting of combined basic material and the oXids of boron and silicon, the last oXid being materially in excess of 73%, said material having a thermal coeicient of eXpansion less than about 3.5X106.

2. A tough, strong glass consisting of the oXid of an alkali metal, magnesium, boron and silicon, the'silicon dioXid being in excess 'of about 7 3%, said glass having a thermal coeiiicient of' expansion less than 3.5X10-6.

1n Witness whereof, li have hereunto set my hand this sixth day of May, 1912.

. EZECHIEL WElNTlR-AUB.

Witnesses:

JOHN A. McManus, Jr., ROBERT SHAND. 

